Textile integration of electronic circuits

ABSTRACT

The present disclosure relates to a method of integrating a interposer device with a textile layer, wherein the interposer device is a stretchable interposer device comprising a stretchable electrically conductive structure with at least one contact pad for establishing at least one electrically conductive path towards the textile layer. The interposer device is arranged to be mechanically attached to a textile layer comprising a plurality of yarns, at least one of which is an electrically conductive yarn. An electrical connection is established between the at least one conductive yarn of the textile layer and the at least one contact pad, which electrical connection is established after the interposer device has been mechanically attached to the textile layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT Application No.PCT/EP2014/052753, filed Feb. 12, 2014, which claims the benefit of U.S.Provisional Application No. 61/765,533, filed Feb. 15, 2013. Each of theabove applications is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technological Field

The present disclosure relates to a method for integrating electroniccircuits with a textile layer containing electrically conductive yarns.More specifically the present disclosure relates to a method ofintegrating a stretchable interposer with a textile layer. The presentdisclosure further relates to a textile fabric containing electricallyconductive yarns and electronic circuits electrically connected to suchelectrically conductive yarns.

2. Description of the Related Technology

Integration of electronic devices or electronic circuits with a textilefabric can add new functionalities to the textile, allowing therealization for example of clothes with integrated sensors, luminoustextile or wearable computing.

U.S. Publication No. 2006/0258205 relates to a method for integrating anelectric component with a textile including a conductor line system, theconductor line system having an arrangement of a plurality of electricconductor lines, the electric component being connected to specificelectric conductor lines. An adapter element is arranged between theelectric component and the conductor line system to redistribute thepads of the component to the conductive lines in the textile. Theadapter element has at one side a connecting portion that is to beconnected to the specific electric conductor lines and on the other sidea connecting portion that is to be connected to the electroniccomponent. Connecting points are first prepared in the conductor linesystem by locally removing the external insulation of the electricconductor lines of the textile. The adapter element is then fixed bymeans of an adhesive that makes a solid mechanical connection with thebasic fabric of the textile. In the portions of the textile connectingpoints an electrically conductive adhesive is provided which allows fora selective electrical connection between the adapter and the textile.This approach requires that the connecting arrangement of the adapterelement is precisely aligned to the arrangement of the conductive linesof the textile in order to avoid faulty connections. However, thealignment accuracy is mainly dependent on the accuracy limitations ofthe placing tool used. For this reason, the use of this approach mayrequire that the size of the connection points (electrical contacts) isrelatively large, so as to compensate for the limited accuracy of theplacing tools used for placing the adapter to the desired connectionpoints on the textile. However, increasing the size of the connectionpoints may limit the flexibility of the textile.

In “Contacting electronics to fabric circuits with nonconductiveadhesive bonding”, T. Linz et al, The Journal of the Textile Institute,Vol. 103, No. 10, October 2012, 1139-1150, a contacting approach basedon nonconductive adhesive bonding is proposed. This approach involvesthe application of pressure to displace an adhesive out of a contactingarea and curing of the adhesive at elevated temperature. Because of theuse of pressure and an elevated temperature, this process is limited totextile materials that are not damaged by the pressures and/ortemperatures used.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

It is an aim of the present disclosure to provide a method forintegrating electronic circuits with a textile containing electricallyconductive yarns that overcomes the problem of the prior art withregards to the accuracy limitations of the placing tools whilemaintaining the flexibility of the textile layer.

This aim is achieved according to the present disclosure with the methodshowing the technical characteristics of the first independent claim.

More in particular according to an embodiment of the present disclosurea method of integrating an interposer device with a textile layer isprovided. The method may comprise the step of providing a stretchableinterposer device that may contain an electronic component, thestretchable interposer device may comprise at a first side a stretchableelectrically conductive structure with at least one contact pad forestablishing at least one electrically conductive path towards anelectrically conductive yarn of the textile layer. The stretchableinterposer may be positioned relative to the textile layer comprising aplurality of yarns, at least one of which is an electrically conductiveyarn, such that the at least one contact pad is aligned with the atleast one electrically conductive yarn thereby defining at least onecontacting location between the interposer device and the textile layer.The stretchable interposer device may be mechanically attached to thetextile layer by means of an electrically non-conductive adhesive suchas glue or plastic. Once the stretchable interposer device is secured onthe textile layer at the desired location, an electrical contact may beestablished between the at least one contact pad and the at least oneelectrically conductive yarn at the at least one contacting location.The electrical contact may be established by providing an electricallyconductive material at the at least one contacting location so that anelectrically conductive contact is formed between the respective contactpad and the respective electrically conductive yarn.

It has been found that performing the step of establishing an electricalcontact after the step of mechanically attaching the interposer deviceto the textile layer may significantly reduce the misalignment issuesassociated with the accuracy limitations of the tools used for placingthe interposer device, which may result in the size reduction of theelectrical contacts thereby greatly maintaining the flexibility of thetextile layer.

According to an embodiment of the present disclosure, the step ofestablishing an electrical contact may comprise the step of locallyremoving, at the contacting locations defined, electrically insulatingmaterials present between the at least one contact pad and the at leastone electrically conductive yarn. Locally removing electricallyinsulating materials may for example comprise locally removingencapsulation material and/or supporting material of the stretchableinterposer and/or locally removing an insulating coating of electricallyconductive yarns and/or locally removing non-conductive adhesivematerial used for mechanically attaching the interposer device to thetextile layer.

By locally removing the insulating materials after the interposer deviceis mechanically attached to the textile layer it has the advantage thatthe contacting location is defined after the interposer device issecured on the textile layer. As a result, it is ensured that anymisalignment introduced during any of the previous steps is compensated,which may lead to a further reduction in the size of the electricalcontacts. Furthermore, defining the at least one contacting locationafter the interposer is attached to the textile layer may have as anadvantage that the connecting arrangement of the interposer device isnot required to be precisely aligned to a specific location of thearrangement of the conductive yarns of the textile. This may result inthe relaxation of the alignment requirements between the interposerdevice and the textile thereby making it possible to use cheaper placingtools with lower alignment accuracy.

According to an embodiment of the present disclosure, the stretchableinterposer may comprise a supporting layer arranged for supporting theat least one contact pad. In this case the step of locally removing theinsulating materials may comprise the formation of at least one openingon the supporting layer at the at least one contacting location so as toexpose the at least one contact pad.

According to an embodiment of the present disclosure, the step oflocally removing the insulating material may be performed by means oflaser ablation, which may require that the laser is aligned with thelocation of the contact pads of the interposer so that insulatingmaterials are removed only from the desired contacting locations. Thelaser alignment may be performed by illuminating the textile, from theside where the interposer is attached, such that the underlying at leastone contact pads arranged on the interposer device becomes visible. Thelaser ablation may be performed either from the textile side or from thefirst side of the interposer device. By using laser ablation the step oflocally removing insulating material may be better controlled such thatthe insulating materials are only removed from the desired contactinglocations which may lead to a further reduction in the size of theelectrical contacts required. Furthermore, the use of laser ablation mayovercome the problems related to the use of etching chemicals forlocally removing insulating material which may negatively react with thetextile fabric and/or other material of the structure, such as themetals contacts and the electrically conductive yarns of the textilelayer.

According to an embodiment of the present disclosure, the step ofmechanically attaching the interposer device to the textile layer maycomprise arranging an electrically non-conductive adhesive between thetextile layer and the interposer device. For example, a patterned layerof non-cured adhesive material may be provided on the textile layer atlocations where the interposer is to be attached, followed by placingthe interposer on the layer of adhesive material, and curing the layerof adhesive material. The electrically non-conductive adhesive may beprovided either on the textile layer or on the stretchable interposerdevice. In a further example, a layer of non-cured adhesive material maybe provided on a surface of the interposer, followed by placing theinterposer on the textile layer with the surface having the non-curedadhesive material layer oriented towards the textile layer, and curingthe layer of adhesive material. For example, the electricallynon-conductive adhesive material can be a silicone-based material.Furthermore, at least one encapsulation layer may be provided for atleast partly encapsulating the interposer device. The encapsulationlayer may be made from a non-cured stretchable insulating material,preferably a polymer-based material such as Polydimethylsiloxane (PDMS)or Thermoplastic Polyurethane (TPU). Providing a stretchableencapsulation layer may offer the advantage that the mechanical stressgenerated during the deformation of textile fabric may be greatlyabsorbed, such that the reliability of more rigid parts is not affected.For example, the risk of breaking an electrical contact between the atleast one contact pad and the at least one conductive yarn duringdeformation of the textile fabric may be greatly reduced or completelyeliminated.

According to an embodiment of the present disclosure, the step ofestablishing an electrical contact may be performed by providing at thedesired contacting location an electrically conductive material forelectrically connecting the at least one conductive yarn with the atleast one contact pad. For example, a non-cured electrically conductiveadhesive material may be provided at each of the contacting locationsfrom the textile side. According to another example, the electricallyconductive adhesive may be provided at the contacting locations from theinterposer device side. The electrically conductive adhesive may be forexample an isotropic conductive adhesive material containing metalparticles such as silver particles. The electrically conductive adhesivemay be cured at a separate step at a low temperature.

According to embodiments of the present disclosure, the materials of theelectrically non-conductive adhesive, and/or encapsulation layer, and/orthe electrically conductive adhesive may be chosen such that they can becured at a low temperature. For example, at a curing temperature, of atleast 15.0 degrees, preferably at most 40.0 degrees, more preferably atmost 30.0 degrees, and even more preferably at most 25.0 degrees.

The use of material having low curing temperatures may enable theintegration of electronic circuits with different types of textilefabrics, since temperature related textile damage can be avoided.

According to an embodiment of the present disclosure, the at least onecontact pad arranged on the first side of the stretchable interposerdevice may be provided in a variety of shapes and sizes. For example,the at least one contact pad may have a ring shape with a centralopening. The central opening may be used as an alignment marker forperforming the step of locally removing insulating material, for exampleby means of laser ablation, from the interposer side. Using features ofthe at least one contact pad as alignment markers may eliminate the needfor placing extra alignment markers at different locations on theinterposer device thereby reducing the area overhead of the interposer.

According to an embodiment of the present disclosure, the stretchableelectrically conductive structure arranged on the interposer device maycomprise one or more stretchable interconnects. For example, eachstretchable interconnect may comprise a meander-shaped metal track,which is arranged to stretch in response to a deformation of the textilelayer. The use of stretchable interconnects may further enhance theabsorption of mechanical stress caused during the deformation of thetextile layer, which mechanical stress may compromise the reliability ofthe electrical contacts between the contact pads and the respectiveconductive yarns. Furthermore, the stretchable interconnects may beembedded in an encapsulation material, wherein the encapsulationmaterial can be removed from between different meandered electricalconnections, thereby strongly reducing the contact area between thetextile and the integrated interposer and thus better maintaining themechanical properties of the textile, without affecting the electricalproperties of the electrical connections.

According to an embodiment of the present disclosure, the processingsteps of the method may be adapted such they are ‘textile friendly’ sothat the risk of damaging the textile is limited or completelyeliminated. Furthermore, the processing steps of the method may beperformed without applying pressure or at very low pressure and at lowtemperatures, e.g. at temperatures in the range between about 15° C. andabout 40° C. The temperatures used during processing may be selecteddepending on the type of textile used. For example, in the case ofcotton, temperatures up to about 130° C. can be used. For other types oftextile temperatures up to about 80° C. may be used. However, inpreferred embodiments the temperatures are below 40° C. It is anadvantage of an inventive aspect that the chemical steps and chemicalmaterials used (e.g. for adhesion) are not aggressive and thus don'taffect the textile properties.

It is an advantage of embodiments of the present disclosure, that themethod may be highly textile type independent. For example, it may beused in combination with a broad range of different types of textile. Ina further example, the method may be used in combination with differenttypes of carrier textile, such as for example cotton, silk, polyester,etc. In yet another example, the method may be used in combination withdifferent types of conductive yarns, such as conductive yarns comprisingconductive wires with or without an insulating coating or conductiveyarns comprising a non-conductive core with at least one electricallyconductive wire wrapped around it. In yet another example, the methodmay be used in combination with a textile layer comprising conductiveyarns formed for example by ink printing electrically conductive lineson a textile layer.

According to a second aspect of the present disclosure, a textile fabricmay be provided, which may comprise a stretchable interposer deviceintegrated with a textile layer of the textile fabric according to thefirst aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be further elucidated by means of the followingdescription and the appended figures.

FIGS. 1( a) and 1(b) show partial cross sections of a stretchableinterposer that can be used in one embodiment. FIG. 1( a) illustrates afully encapsulated interposer. FIG. 1( b) illustrates a single sideencapsulated interposer.

FIGS. 2( a) and 2(b) show partial cross sections of a stretchableinterposer mechanically attached to a textile layer by means of anadhesive, for a fully encapsulated interposer (FIG. 2( a)) and for asingle side encapsulated interposer (FIG. 2( b)).

FIGS. 3( a) and 3(b) show partial cross sections of a device after locallaser ablation of insulating layers, for a fully encapsulated interposer(FIG. 3( a)) and for a single side encapsulated interposer FIG. 3( b)).

FIGS. 4( a) and 4(b) show partial cross sections of a device afterfilling of the laser ablated via with an electrically conductivematerial in accordance with an inventive aspect, for a fullyencapsulated interposer (FIG. 4( a)) and for a single side encapsulatedinterposer (FIG. 4( b)).

FIGS. 5( a) and 5(b) show partial cross sections of a device accordingto an inventive step after providing an insulating layer, for a fullyencapsulated interposer (FIG. 5( a)) and for a single side encapsulatedinterposer (FIG. 5( b)).

FIG. 6( a) and FIG. 6( b) show a partial cross section of a stretchableinterposer with a ring shaped contact pad, as can be used in oneembodiment. FIG. 6( a) illustrates a fully encapsulated interposer; FIG.6( b) illustrates a single side encapsulated interposer. FIG. 6( c)shows a top view of a ring shaped contact pad.

FIGS. 7( a) and 7(b) show partial cross sections of a stretchableinterposer mechanically attached to a textile layer by means of anadhesive, for a fully encapsulated interposer (FIG. 7( a)) and for asingle side encapsulated interposer (FIG. 7( b)), wherein the interposerhas a ring shaped contact pad.

FIGS. 8( a) and 8(b) show partial cross sections of a device after locallaser ablation of insulating layers, for a fully encapsulated interposer(FIG. 8( a)) and for a single side encapsulated interposer FIG. 8( b)),wherein the interposer has a ring shaped contact pad.

FIGS. 9( a) and 9(b) show partial cross sections of a device afterfilling of the laser ablated via with an electrically conductivematerial according to an embodiment of the present disclosure, for afully encapsulated interposer (FIG. 9( a)) and for a single sideencapsulated interposer (FIG. 9( b)), wherein the interposer has a ringshaped contact pad.

FIGS. 10( a) and 10(b) show partial cross sections of a device accordingto an embodiment of the present disclosure after providing encapsulatinginsulating layers, for a fully encapsulated interposer (FIG. 10( a)) andfor a single side encapsulated interposer (FIG. 10( b)), wherein theinterposer has a ring shaped contact pad.

FIG. 11( a) to 11(e) schematically illustrate process steps of a methodaccording to an embodiment of the present disclosure.

FIG. 12 schematically shows an example of an interposer as may be usedin a method of the present disclosure.

DETAILED DESCRIPTION OF CERTAIN ILLUSTRATIVE EMBODIMENTS

The present disclosure will be described with respect to particularembodiments and with reference to certain drawings but the disclosure isnot limited thereto but only by the claims. The drawings described areonly schematic and are non-limiting. In the drawings, the size of someof the elements may be exaggerated and not drawn on scale forillustrative purposes. The dimensions and the relative dimensions do notnecessarily correspond to actual reductions to practice of thedisclosure.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order. The terms are interchangeable under appropriatecircumstances and the embodiments of the disclosure can operate in othersequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. The terms so used areinterchangeable under appropriate circumstances and the embodiments ofthe disclosure described herein can operate in other orientations thandescribed or illustrated herein.

Furthermore, the various embodiments, although referred to as“preferred” are to be construed as exemplary manners in which thedisclosure may be implemented rather than as limiting the scope of thedisclosure.

The term “comprising”, used in the claims, should not be interpreted asbeing restricted to the elements or steps listed thereafter; it does notexclude other elements or steps. It needs to be interpreted asspecifying the presence of the stated features, integers, steps orcomponents as referred to, but does not preclude the presence oraddition of one or more other features, integers, steps or components,or groups thereof. Thus, the scope of the expression “a devicecomprising A and B” should not be limited to devices consisting only ofcomponents A and B, rather with respect to the present disclosure, theonly enumerated components of the device are A and B, and further theclaim should be interpreted as including equivalents of thosecomponents.

In the context of the present disclosure, the term stretchableinterposer may be interpreted as a planar stretchable device containingat least one stretchable interconnection and at least one contact pad.The at least one stretchable interconnection and the at least onecontact pad may be embedded or encapsulated in a stretchableencapsulation material such as a stretchable polymer. The at least onestretchable interconnection can for example contain meander shapedtracks containing a metal layer, preferably containing a stack of ametal layer and a flexible supporting layer such as a polyimide layer, aPET (polyethylene terephthalate) layer or a PEN (polyethylenenaphthalate) layer. Additional layers may be present, such as forexample a protective coating covering the metal layer, for example toprovide protection against moisture and/or chemicals. In addition to theat least one stretchable interconnection and the at least one contactpad, the stretchable interposer can contain electronic components orelectronic circuits, the electronic components or circuits preferablybeing embedded or encapsulated in a stretchable encapsulation material.Using an interposer that only contains interconnections and contact padsmay for example be used for making an electrical connection between twonon-crossing conductive yarns of the textile. Each stretchableinterconnection may be in electrical contact with at least one contactpad.

In the context of the present disclosure, the term flexible may beinterpreted as non-stiff, non-rigid, i.e. bendable but not stretchable.A flexible structure is adapted to be deformable in a certain directionduring normal use of the structure, but does not elongate. The lengthdoes not change during bending.

In the context of the present disclosure, the term stretchable means maybe interpreted as resilient. i.e. elastically deformable withelongation. A stretchable structure is adapted to be elasticallydeformed during normal use (with elongation).

According to embodiments of the present disclosure a method ofintegrating a stretchable interposer, e.g. a stretchable interposercontaining an electronic circuit, with a textile layer containingelectrically conductive yarns may be provided. According to embodimentsof the present disclosure a textile fabric comprising a textile layerwith electrically conductive yarns and a stretchable interposer, e.g. astretchable interposer containing an electronic circuit, electricallyconnected to such electrically conductive yarns may further be provided.

Although the present disclosure is described herein with references tothe use a stretchable interposer, the disclosure is not limited thereto.For example, according to embodiments of the present disclosure aflexible interposer may also be used instead of a stretchableinterposer.

In a method according to embodiments of the present disclosure, astretchable interposer may be provided that is designed and optimizedfor a predetermined textile integrated application. In a first step amechanical connection may be established between the stretchableinterposer and a textile fabric or textile layer, so that thestretchable interposer is mechanically attached to the textile layer.The stretchable interposer may contain at least one contact pad. The atleast one contact pad may for example have a circular shape, but anyother suitable shape can be used. The at least one contact pad maycontain a metal such as Cu. The diameter of a contact pad may betypically in the range between about 0.5 mm and about 1 mm, the presentdisclosure not being limited thereto. The stretchable interposer mayfurther comprise stretchable interconnections, such as meandered metalinterconnections, e.g. having a track width in the order of about 100micrometer, in electrical contact with one or more contact pads arrangedonto a first side of a stretchable interposer. In preferred embodimentsthe meandered metal interconnections may contain a stack of layerscomprising a metal layer and a supporting layer such as a polyimidelayer or any other suitable flexible electrically insulating layer suchas a PET layer or a PEN layer. The supporting layer may also be presentadjacent to the at least one contact pad, for example the metal layer ofthe at least one contact pad may be arranged on the supporting layer,which may be a patterned supporting layer. According to embodiments ofthe present disclosure, a circular contact pad with a diameter largerthan the size of the meander tracks may be provided for establishing anelectrical contact between the meander tracks and the conductive yarnsof the textile fabric. The textile fabric may contain conductive yarnsembedded in an insulating material, the present disclosure not beinglimited thereto. For example, the conductive yarns may have a diameterin the range between about 20 micrometer and about 100 micrometer.Furthermore, the conductive yarns may be arranged in the textile layerat distance from one another, pitch, which may be in the range of about1 mm and about 5 mm. However, the present disclosure is not limitedthereto, and other suitable diameters and/or distances between theconductive yarns may be used.

FIGS. 1( a) and 1(b) show examples of cross sections of a stretchableinterposer according to embodiments of the present disclosure. FIG. 1(a) shows an example of a fully, also referred to hereinafter as doubleside, encapsulated stretchable interposer having a stretchableelectrically non-conductive encapsulation layer at both sides of theinterposer. FIG. 1( b) shows a cross section of a further example of astretchable interposer where a single side encapsulated interposer isprovided with the encapsulation layer arranged only at one of theinterposer sides. The encapsulation layer may be a polymer material,which can be either cured or un-cured, such as PDMS(Polydimethylsiloxane) or a TPU (Thermoplastic Polyurethane). FIG. 1( a)shows a cross section of an interposer according to embodiments of thepresent disclosure, comprising a patterned flexible electricallynon-conductive supporting layer 10 (such as a polyimide layer or a PETor PEN layer and a contact pad 11 arranged on the supporting layer 10.For example the supporting layer 10 and the contact pad 11 may be fullyencapsulated by a first encapsulation layer 21 provided at a first sideof the interposer and a second encapsulation layer 22 provided at asecond side of the interposer. The interposer may comprise additionallayers, such as for example a protective layer or a coating layer (notshown) arranged for protecting the contact pad 11 and/or other metallayers provided at a side opposite to the side of the supporting layer10. FIG. 1(b) shows a cross section of a single side encapsulatedinterposer according to embodiments of the present disclosure having asupporting layer 10, contact pad 11 and a first encapsulation layer 21arranged at the first side of the interposer.

According to embodiments of the present disclosure, the interposer maybe single side encapsulated by providing a second encapsulation layer atthe second side of the interposer and no encapsulation layer on thefirst side. In other embodiments (not shown) the interposer may comprisea double sided flex board, with contact pads 11 at both sides of thesupporting layer 10. In still other embodiments, a part of theinterposer containing electronic components or electronic circuits maybe encapsulated, and another part of the interposer containing contactpads may be non-encapsulated. In other embodiments the interposer may benon-encapsulated.

FIG. 12 schematically shows an example of a stretchable interposeraccording to embodiments of the present disclosure. In the exampleshown, the interposer comprises stretchable interconnections 101, eachstretchable interconnection being connected to a contact pad 102. Theinterposer further contains electronic components 103, the electroniccomponents 103 being electrically connected to at least one contact pad102 by a corresponding stretchable interconnection 101 and electricallyconductive tracks 104. The electrically conductive tracks 104 are shownin FIG. 12 as straight lines, but they may have a different shape, suchas for example a meander shape. In the example shown in FIG. 12, thestretchable interposer is partially encapsulated in an encapsulationmaterial 100. The dashed lines 33 in FIG. 12, which are not part of theinterposer, schematically represent electrically conductive wires of atextile layer to which the contact pads 102 of the interposer may beconnected according to embodiments of the present disclosure.

By using a double side encapsulated interposer as shown in FIG. 1( a)damage to the stretchable interposer, e.g. due to mechanical or chemicalinfluences, can be avoided. The risk of damage to the interposer may forexample be related to the environment where the interposer is storedbetween its production and the integration process and to the timeinterval between production and integration.

The use of a single side encapsulated interposer, such as the one shownin FIG. 1( b), may have as an advantage that the production cost of thetextile integration can be substantially reduced. The cost reduction maybe achieved due to the reduced number of processing steps, lower use ofmaterial quantities, and less insulating material to be removed, asdescribed herein.

Furthermore, the use of a partially encapsulated interposer may furtherenable the removal of any electrically insulating material beforeattaching the stretchable interposer to the textile layer. For example,in the case where an interposer similar to the one shown in FIG. 12 iscombined with a textile layer containing electrically conductive yarnswithout insulating coating, the insulating material of the interposermay be removed prior to the step of mechanically attaching theinterposer to the textile. Therefore, the use of partially encapsulatinginterposer devices may eliminate the need for removing insulatingmaterial after the interposer has been mechanically attached to thetextile, for example by means of laser processing, i.e. no need for adedicated laser.

According to an embodiment of the present disclosure, the stretchableinterposer may be firstly mechanically attached to a textile layer.Hereinafter it is assumed that the interposer is attached with itssecond side i.e. the side of the supporting layer 10 facing the textilelayer. However, the present disclosure is not limited to this embodimentand the interposer may also be attached with its first side facing thetextile layer i.e. the side where the metal layers are arranged.

According to an embodiment of the present disclosure, the step ofmechanically attaching the interposer device to the textile may comprisethe step of providing a first mask on the textile layer, e.g. byproviding a patterned foil or mask having openings at the desiredlocations where a stretchable interposer is to be attached. Anelectrically non-conductive adhesive material may then be provided onthe mask or foil, e.g. by casting or screen printing. The non-conductiveadhesive material may preferably be a polymer material that can be curedat low temperatures, such as e.g. at a temperature in the range betweenabout 15° C. and about 40° C. For example, the adhesive material may bea silicone material, an acrylic material or an epoxy material. Afterremoving the mask, a patterned layer of non-cured adhesive may bepresent at the locations where the interposer is to be attached. Nextthe interposer may be placed on the layer of uncured adhesive, and theadhesive is cured, e.g. by UV curing or by curing at a suitable curingtemperature. The curing temperature can be selected based on the type oftextile used in the process. For example, when using a cotton textilethe curing temperature may be as high as 130° C. For other textilematerials the curing temperature may be lower than about 40° C., e.g.not higher than about 25° C. It may be an advantage of using highercuring temperatures that the curing time may be shorter.

FIGS. 2( a) and 2(b) show different examples of a structure resultingfrom the integration of a stretchable interposer with a textile layer30. FIG. 2( a) shows a double side encapsulated interposer integratedwith a textile layer 30. FIG. 2( b) shows a single side encapsulatedinterposer integrated with a textile layer 30. FIGS. 2( a) and 2(b) showthe cured adhesive layer 23 between the interposer and the textile layer30, the textile layer containing a combination of non-conductive yarns31 and electrically conductive yarns 32. However, other types of textilemay be used according to embodiments of the present disclosure,comprising only electrically conductive yarns 32. In the example shownin FIGS. 2( a) and 2(b), the electrically conductive yarns 32 comprise aconductive wire 33 and an electrically insulating encapsulation orcoating 34. The electrically insulating coating 34 may for example bemade from a thermoplastic material such as polyurethane.

It is noted that the figures show a cross-section of the textile layer30 and the interposer device at the location of a single contact pad 11of the interposer. In practical applications the interposer may comprisea plurality of contact pads 11. In addition, the interposer may comprisestretchable interconnections 101 and electronic devices or electroniccircuits 103 as illustrated in the example shown in FIG. 12. Inpractical applications the lateral dimensions of the textile layer maybe much larger than the lateral dimensions of the interposer.

According to an embodiment of the present disclosure, the step ofmechanically attaching the interposer to the textile layer may beperformed by providing a layer of uncured adhesive on the stretchableinterposer rather than on the textile layer. For example, after theadhesive layer is applied on the stretchable interposer, the interposermay be positioned on the textile layer at a predetermined location, andthe adhesive layer is cured. By providing the adhesive layer on thestretchable interposer it may eliminate the need for providing adedicated mask. At a next step, insulating material may be removed atcontacting locations where an electrical contact is to be made between aconductive wire 33 of the textile layer 30 and a contact pad 11 of thestretchable interposer. The step of removing the insulating material maybe performed by laser ablation. It is an advantage of using laserablation that there is no need for using chemicals that may interactwith the textile. The laser ablation may for example be done from thetextile side of the structure. In the examples shown in the figures, thefollowing materials may be removed locally during the step of locallyremoving insulating materials: the insulating coating 34 of theconductive yarn, the non-conductive adhesive layer 23 between thestretchable interposer and the textile layer 30, the secondencapsulation layer 22 if present, and the non-conductive flexiblesupporting layer 10.

According to an embodiment of the present disclosure, the laser ablationmay be performed by a YAG laser arranged for removing thermoplasticmaterials and polyimide. However, the YAG laser may be less preferablefor removing PDMS materials, such as for example the material used forthe second encapsulation layer 22. In preferred embodiments thedifferent insulating layers may be removed by means of a CO2 laser. Itis an advantage of using a CO2 laser that it allows good removal of thedifferent materials in a time efficient way. It is an additionaladvantage of the use of CO2 laser in that it does not significantlyaffect the properties of the metals layers used, e.g. the metals formingthe conductive yarns and forming the contact pads.

FIGS. 3( a) and 3(b) show different examples of a structure according toembodiments of the present disclosure after the step of locally removinginsulating material has been performed, for example by means of laserablation. FIG. 3( a) shows an example of a resulting structurecomprising a double side encapsulated interposer. FIG. 3( b) shows afurther example of a resulting structure comprising a (single sided)encapsulated interposer. It is an advantage of removing the differentmaterials from the textile side of the structure that the firstencapsulation layer 21 may serve as a protection layer, e.g. againstmoisture. The first encapsulation layer 21 also may serve as aninsulator at the first side of the interposer. The non-conductiveadhesive layer 23 and the electrically insulating coating 34 may act asan insulator at the sidewalls of the opening made by the laser ablationstep.

According to embodiments of the present disclosure, the step of locallyremoving insulating material by means of a laser may require that thelaser is aligned with the contact pad 11 of the interposer. In the casewhere the interposer device comprises a supporting layer 10, a via oropening may be formed at the desired location during the step of locallyremoving the insulating material such that the contact pad can beaccessed. The size of the opening or via made through the differentlayers may preferably be smaller than the size of the contact pad 11,such that the contact pad 11 extends at all sides over the edges of thevia. For example, the via diameter may be about 100 micrometer smallerthan the diameter of the contact pad. However, the present disclosure isnot limited thereto and the via may have different diameters. The viamay be filled at a subsequent step with an electrically conductivematerial, such as e.g. an electrically conductive adhesive, to establishan electrical connection between the contact pad 11 of the interposerand the exposed electrically conductive wires 33 of the conductiveyarns. Preferably the time interval between the step of locally removingthe insulating material and the step of filling the via may besufficiently short to avoid or limit oxidation of the exposed conductivesurfaces.

In the examples described herein, filling of the via with a conductiveadhesive material may be performed from the textile side of thestructure. For example, filling of the via may be done by dispensing anelectrically conductive adhesive material, followed by curing. FIGS. 4(a) and 4(b) show different examples of a structure according toembodiments of the present disclosure, after the steps of filling thevia with a conductive adhesive material 35 and curing have beenperformed. FIG. 4( a) shows an example of a resulting structurecomprising a double side encapsulated interposer. FIG. 4( b) shows afurther example of a resulting structure comprising a single sideencapsulated interposer.

According to embodiments of the present disclosure, an electricallyinsulating layer 36, such as a PDMS layer, may be provided at asubsequent step for locally encapsulating the textile layer at thelocations where the adhesive material 35 is exposed. The encapsulationlayer 36 may further be cured so that a totally insulated device may beobtained, which is protected e.g. against external influences such asmechanical influences, humidity or chemicals. Preferably the insulatinglayer 36 may be provided such that it fully covers the exposed area ofthe adhesive material 35 thereby overcoming the insulation problemsresulting from moisture penetrating from neighbouring yarns. FIGS. 5( a)and 5(b) show different examples of the resulting structure having anencapsulation layer at the locations where the adhesive layer isexposed. FIG. 5( a) shows an example of a resulting structure comprisinga double side encapsulated interposer. FIG. 5( b) shows an example of aresulting structure comprising (single side) encapsulated interposer.

According to an embodiment of the present disclosure, the step oflocally removing the insulating materials by means of laser ablation maybe performed from the interposer side rather than the textile side. Insuch embodiments a stretchable interposer may be used comprising contactpads having a shape with an opening, e.g. a central opening, such as aring shape.

FIGS. 6( a) and 6(b) show cross sections of stretchable interposerscomprising a contact pad 51 having a shape with an opening. The figuresonly show the interposer at the location of a single contact pad 51. Inpractical applications the interposer may contain a plurality of contactpads 51. In addition, the stretchable interposer may contain stretchableinterconnections 101 and it may also contain electronic components ordevices and/or electronic circuits 103 as illustrated in the exampleshown in FIG. 12. FIG. 6( c) shows a top view of a contact pad 51 havinga ring shape with a central opening 52. The stretchable interposer maybe double side encapsulated, as shown in the cross section of FIG. 6(a), or it may be encapsulated only at the first side, as shown in thecross section of FIG. 6( b). In other embodiments (not shown) aninterposer may have only a second encapsulation layer provided at thesecond side of the interposer and no encapsulation layer at the firstside. In other embodiments (not shown) the interposer may contain adouble sided flex board, with contact pads 51 at both sides of thesupporting layer 10.

FIGS. 7( a) and 7(b) show different examples of a structure according toembodiments of the present disclosure. The stretchable interposer may bemechanically attached to a textile layer as described above. Anelectrically non-conductive adhesive layer may be provided either at thesecond side of the stretchable interposer or on the textile layer. Thestretchable interposer may be positioned on the textile layer at apredetermined location after which the adhesive layer may be cured.FIGS. 7( a) and 7(b) show exemplified cross sections of the resultingstructure for a double side encapsulated interposer, as shown in FIG. 7(a), and for a single side encapsulated interposer, as shown in FIG. 7(b). At a next step, insulating material may be removed at locationswhere a contact is to be made between a conductive wire 33 of thetextile layer 30 and contact pad 51 of the stretchable interposer,thereby forming a via. For example, the removal of the insulatingmaterial may be performed using laser ablation. In the examplesdescribed herein, the laser ablation may be performed from theinterposer side of the structure, i.e. the side opposite to the textileside of the structure. In the examples described herein, the followingmaterials may be locally removed during the step of locally removinginsulating materials: the first encapsulation layer 21, thenon-conductive flexible supporting layer 10, the second encapsulationlayer 22 if present, the non-conductive adhesive layer 23 between thestretchable interposer and the textile layer, and the insulating coating34 of the conductive yarn. The ring shaped contact pad may be used as analignment marker (element) or mask for the laser ablation step.Furthermore, the laser ablation parameters are adapted such that onlyinsulating materials are removed thereby minimizing the impact of laserablation to the metals. FIGS. 8( a) and 8(b) show different examples ofa structure according to embodiments of the present disclosure afterlaser ablation has been performed. FIG. 8( a) shows an example of aresulting structure comprising a double side encapsulated interposer.FIG. 8( b) shows an example of a resulting structure comprising a(single side) encapsulated interposer. It is an advantage of using acontact pad having a shape with an opening and of performing the laserablation from the interposer side that it allows a good and easyalignment of the laser with the contact pad.

At a next step, the via formed by the laser ablation step may be filledwith an electrically conductive material. e.g. an isotropic conductiveadhesive, to establish an electrical connection between the contact pad51 of the interposer and the exposed electrically conductive wires 33.FIGS. 9( a) and 9(b) show different examples of a resulting structureafter the steps of filling the via has been performed. FIG. 9( a) showsan example of a resulting structure comprising a double sideencapsulated interposer. FIG. 9( b) shows a further example of aresulting structure comprising a (single side) encapsulated interposer.

Preferably, at a next step insulating layers may be provided at bothsides of the structure to avoid penetration of moisture that could causeelectrical shorts in the electronic devices arranged in the interposerdevice. FIGS. 10( a) and 10(b) show examples of providing insulatingmaterial on both sides of the structure for a double side encapsulatedinterposer and for a single side encapsulated interposer respectively.

FIGS. 11( a) to 11(e) show further examples of the structure accordingto an embodiment of the present disclosure, where a partiallyencapsulated stretchable interposer may be used, such as the interposershown in FIG. 12, whereby the encapsulation layer may be provided suchthat the part of the interposer containing contact pads is notencapsulated while the part of the interposer containing electroniccomponents or electronic circuits may be encapsulated. Alternatively, anon-encapsulated interposer may be used.

FIG. 11( a) shows a cross section of an interposer at the location of acontact pad 51, comprising a metal layer with an underlying supportinglayer 10, and FIG. 11( b) shows a corresponding top view. In practicalapplications the interposer may contain a plurality of contact pads 51.In the example shown, the contact pad 51 has a circular shape with acentral opening 52.

As previously discussed, a partially encapsulated interposer may forexample be obtained by first fabricating a fully encapsulatedinterposer, and then locally removing, for example by means of laserablation, the encapsulation material and any other insulating materialthat may be present between the contact pad 51 and the side of theinterposer to be attached to the textile. A partially encapsulatedinterposer may also be obtained directly, for example by partiallyencapsulating the interposer.

The partially encapsulated stretchable interposer may be mechanicallyattached to a textile layer by means of an electrically non-conductiveadhesive layer. Preferably a layer of uncured adhesive material may beprovided at the side of the stretchable interposer to be attached to thetextile layer. The stretchable interposer may then be positioned on thetextile layer at a predetermined location and the adhesive layer iscured. A cross section of the resulting structure is shown in FIG. 11(c), showing the cured adhesive layer 23 between the interposer and thetextile layer 30. In the example of FIG. 11( c), the textile layercomprises electrically non-conductive yarns 31 and electricallyconductive wires 33 without insulating coating. Other types of textileand other types of conductive yarns may be used such as textile layercomprising a conductive wire with an insulating coating. It is anadvantage of using a textile layer comprising electrically conductivewires without insulating coating that there is no need for removinginsulating material after attachment of the interposer to the textilelayer 30.

In a further step, an electrically conductive material, e.g. anisotropic conductive adhesive, may be provided at the location of thecontact pad to establish an electrical connection between the contactpad 51 of the interposer and the electrically conductive wires 33. Thisstep may be performed by dispensing a conductive adhesive material atthe desired location, followed by curing. FIG. 11( d) shows the anexample of the structure after this process step, where the curedconductive adhesive material 35 electrically connects the contact pad 51with the electrically conductive wires 33.

Insulating layers, for example PDMS layers or polyurethane layers, mayfurther be provided at both sides of the structure to provide mechanicalprotection and to avoid penetration of moisture that could causeelectrical shorts in the electronic devices. FIG. 11( e) shows thestructure having a first insulating layer 39 at the first side and asecond insulating layer 40 at the second side.

The foregoing description details certain embodiments of the disclosure.It will be appreciated, however, that no matter how detailed theforegoing appears in text, the disclosure may be practiced in many ways.It should be noted that the use of particular terminology whendescribing certain features or aspects of the disclosure should not betaken to imply that the terminology is being re-defined herein to berestricted to including any specific characteristics of the features oraspects of the disclosure with which that terminology is associated.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the technology without departing from the spirit ofthe invention.

What is claimed is:
 1. A method of integrating an interposer device witha textile layer, the method comprising the steps of: providing a textilelayer comprising a plurality of yarns, at least one of which is anelectrically conductive yarn; providing a stretchable interposer devicecomprising a stretchable electrically conductive structure with at leastone contact pad for establishing at least one electrically conductivepath towards an electrically conductive yarn of the textile layer;positioning the interposer device such that at least one of its contactpads is aligned with at least one of the electrically conductive yarnsof the textile layer, thereby defining at least one contacting locationbetween the interposer device and the textile layer; mechanicallyattaching the interposer device to the textile layer; and establishingan electrical contact between the at least one contact pad and the atleast one electrically conductive yarn at the at least one contactinglocation, wherein the step of establishing an electrical contact isperformed after the step of mechanically attaching the interposer deviceto the textile layer and wherein the step of establishing an electricalcontact comprises locally removing, at the at least one contactinglocation, electrically insulating materials present between the at leastone contact pad and the at least one electrically conductive yarn, andproviding an electrically conductive material at the at least onecontacting location so that an electrically conductive contact is formedbetween the respective contact pad and the respective electricallyconductive yarn.
 2. The method according to claim 1, wherein theinterposer device comprises a supporting layer.
 3. The method accordingto claim 2, wherein the step of locally removing the insulatingmaterials comprises the formation of at least one opening in thesupporting layer at the at least one contacting location.
 4. The methodaccording to claim 1, wherein the step of locally removing theinsulating materials is performed by laser ablation.
 5. The methodaccording to claim 4, wherein the laser ablation is performed from thetextile layer side.
 6. The method according to claim 4, wherein thelaser ablation is performed from the interposer device side.
 7. Themethod according to claim 1, wherein the step of mechanically attachingthe interposer device to the textile layer comprises the step ofarranging an electrically non-conductive adhesive between the textilelayer and the interposer device.
 8. The method according to claim 7,wherein the step of mechanically attaching the interposer device to thetextile layer further comprises the step of curing the electricallynon-conductive adhesive, thereby providing a permanent bond between thetextile layer and the interposer device.
 9. The method according toclaim 1, wherein the step of providing an electrically conductivematerial at the predetermined contact location is performed from thetextile layer side.
 10. The method according to claim 9, wherein theelectrically conductive material is an isotropic conductive adhesivematerial comprising metal particles.
 11. The method according to claim1, wherein the step of providing an electrically conductive material atthe predetermined contact location comprises the step of curing theelectrically conductive material for providing a permanent bond betweenthe respective contact pad and the respective electrically conductiveyarn.
 12. The method according to claim 1, wherein the method furthercomprises the step of providing at least one encapsulation layer for atleast partly encapsulating the interposer device.
 13. The methodaccording to claim 12, wherein the encapsulation layer is made from astretchable insulating polymer-based material.
 14. The method accordingto claim 12, wherein the method further comprises the step of curing theat least one encapsulating layer.
 15. The method according to claim 8,wherein the curing steps of the method are performed at a curingtemperature of at least 15° C. and at most 25° C.
 16. The methodaccording to claim 11, wherein the curing steps of the method areperformed at a curing temperature of at least 15° C. and at most 25° C.17. The method according to claim 14, wherein the curing steps of themethod are performed at a curing temperature of at least 15° C. and atmost 25° C.
 18. The method according to claim 1, wherein the at leastone contact pad has a central opening.
 19. The method according to claim18, wherein the central opening is used as an alignment marker forperforming the step of locally removing, at the at least one contactinglocation, electrically insulating materials present between the at leastone contact pad and the at least one electrically conductive yarn. 20.The method according to claim 1, wherein the stretchable electricallyconductive structure comprises at least one stretchable interconnect.21. The method according to claim 20, wherein the at least onestretchable interconnect comprises a meander-shaped metal track.
 22. Atextile fabric comprising a stretchable interposer device integratedwith a textile layer of the textile fabric using the method according toclaim 1.